EarthWood - Chill Requirements of Fruit and Nut Trees

Many fruit trees from temperate climates must have a certain amount of cold weather in order to fruit normally. This requirement which varies with the cultivar (and sometimes with the climate) is referred to as chill hours.

There is some disagreement over how to calculate chill hours. Some experts refer to the total number of hours experienced between 0°C and 7°C during the dormancy period. Some offset the chill hours that occur in a 24 hour period by any hours in that same period when the temperature goes above 18°C. And some give extra weight to early season chill hours. To complicate matters, many fruit tree suppliers neglect to mention which method is being used.

There is a shortage of good fruit tree cultivar research. Many fruit tree growers operating in high-chill areas do not have accurate information about the minimum chill hour requirements of some cultivars.

Chill Requirements of Fruit and Nut Trees

Chill hours means accumulated cold-season hours below 7°C.

*Low-chill varieties exist which need less chilling.

Almond 400-700

Apple* 400-1,800

Apricot* 350-1,000

Asian Pear (Chinese) 400-600

Asian Pear (Japanese) 300-750

Avocado 0

Blackberry 200-700

Blueberry (Florida) 0-200

Blueberry (northern) 700-1,200

Chestnut 400-750

Citrus 0

Crabapple 300-500

Currant 800-1,500

European pear 600-1,500

European plum 700-1,800

Fig 100-500

Filbert 800-1,600

Gooseberry 800-1,500

Grape 100-500

Japanese plum* 500-1,600

Kiwi* 400-800

Kiwi 'Twei' (female) 0-200

Kiwi 'Vincent' (female) 0-200

Mulberry 400

Nectarine* 200-1,200

Peach* 200-1,200

Pecan 300-1,600

Persimmon 100-500

Pistachio 800-1,000

Plum-cot 400

Pomegranate 100-200

Quince 100-500

Raspberry* 100-1,800

Sour cherry 700-1,300

Strawberry 200-300

Sweet cherry (most) 600-1,400

Walnut* 400-1,500

Top of page

Chill Hours

Chill Requirements of Fruit and Nut Trees